The present invention relates to a device for banding products, comprising a supply mechanism for supplying band material from a supply roll at an unwinding speed, wrapping means for forming a loop in an end portion of the band material around a space for accommodating products at a banding speed, means for cutting off the end portion and means for closing the loop. Such a device is also known by the name of banding machine.
Banding comprises arranging a wrapper, also called banderole, around one or more products. A banderole is provided for, inter alia, bundling several products, imparting rigidity to one or more products and/or displaying, as an information carrier, information regarding the product.
In existing banding machines, band material is usually supplied in relatively great lengths from a supply roll. Such a supply roll has a relatively large mass inertia. In the prior art, if band material is to be supplied discontinuously and at great speeds, band material is already unwound from the roll before there is a need for band material. In this way a buffer of band material is formed. Existing buffer devices comprise one or more fixedly disposed rotatable cams, over which the band material is passed, and one or more movable guide cams, wherein the movable cams are moved away from the fixed cams in such a manner that the length of the band material being carried over the cams is increased. A drawback of such buffer devices is that undesirable dynamic effects can occur in the case of high feed rates of the band material, as a result of which the band material is unevenly loaded. Because of this, the speeds at which band material can be supplied and retracted are limited, resulting in a limited banding capacity.
Alternative buffer devices make use of gas pressure for applying a force to a free portion of the band material, such that a loop of band material is formed as a buffer. The gas pressure can be quickly increased and decreased without any dynamic effects, so that the building up and reducing of a buffer of band material can take place without machine parts being moved. No mass movement is required, therefore, and thus the maximum load of band material will be manageable, and the speeds at which band material can be supplied and retracted will be significantly higher.
In spite of the increased banding capacity of banding machines with gas pressure buffer devices, even higher supply and retraction speeds are currently desired.